PURPOSE: To measure acceleration using two different procedures.

DESCRIPTION: All gliders are equipped with a 5 cm tab which interrupts the light beam when passing through the photocell gate. The timing system can be set to measure the time, ta or tb, a tab takes to move through the gate or the time, tab, taken for the glider to move from gate A to gate B (not B to A). The timer can be set at full scale ranges from 99.9 ms through 999 seconds for a range of applications.

One timer is set so that it records the time for a glider to move from A to B. The second timer is set to measure the time the tab requires to move through gate A, and then after resetting, the time required for the tab to move through gate B. The acceleration, to an accuracy of less than about ten percent, can be computed using the equation:

a = (v2-v1)/tab = mg/(M=m).

where v1=5cm/ta and v2= 5cm/tb.


REFERENCES: (PIRA 1C20.30) An instruction sheet for the photocell gate timer is available in the Demonstration Reference File.

EQUIPMENT: Air track, gliders, two photocell gate timers, small accelerating masses with audiotape frictionless cord, as photographed.

SETUP TIME: 5 min.

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